/*-------------------------------------------------------------------------
 *
 * win32setlocale.c
 *        Wrapper to work around bugs in Windows setlocale() implementation
 *
 * Copyright (c) 2011-2017, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      src/port/win32setlocale.c
 *
 *
 * The setlocale() function in Windows is broken in two ways. First, it
 * has a problem with locale names that have a dot in the country name. For
 * example:
 *
 * "Chinese (Traditional)_Hong Kong S.A.R..950"
 *
 * For some reason, setlocale() doesn't accept that as argument, even though
 * setlocale(LC_ALL, NULL) returns exactly that. Fortunately, it accepts
 * various alternative names for such countries, so to work around the broken
 * setlocale() function, we map the troublemaking locale names to accepted
 * aliases, before calling setlocale().
 *
 * The second problem is that the locale name for "Norwegian (Bokm&aring;l)"
 * contains a non-ASCII character. That's problematic, because it's not clear
 * what encoding the locale name itself is supposed to be in, when you
 * haven't yet set a locale. Also, it causes problems when the cluster
 * contains databases with different encodings, as the locale name is stored
 * in the pg_database system catalog. To work around that, when setlocale()
 * returns that locale name, map it to a pure-ASCII alias for the same
 * locale.
 *-------------------------------------------------------------------------
 */

#include "c.h"

#undef setlocale

struct locale_map
{
    /*
     * String in locale name to replace. Can be a single string (end is NULL),
     * or separate start and end strings. If two strings are given, the locale
     * name must contain both of them, and everything between them is
     * replaced. This is used for a poor-man's regexp search, allowing
     * replacement of "start.*end".
     */
    const char *locale_name_start;
    const char *locale_name_end;

    const char *replacement;    /* string to replace the match with */
};

/*
 * Mappings applied before calling setlocale(), to the argument.
 */
static const struct locale_map locale_map_argument[] = {
    /*
     * "HKG" is listed here:
     * http://msdn.microsoft.com/en-us/library/cdax410z%28v=vs.71%29.aspx
     * (Country/Region Strings).
     *
     * "ARE" is the ISO-3166 three-letter code for U.A.E. It is not on the
     * above list, but seems to work anyway.
     */
    {"Hong Kong S.A.R.", NULL, "HKG"},
    {"U.A.E.", NULL, "ARE"},

    /*
     * The ISO-3166 country code for Macau S.A.R. is MAC, but Windows doesn't
     * seem to recognize that. And Macau isn't listed in the table of accepted
     * abbreviations linked above. Fortunately, "ZHM" seems to be accepted as
     * an alias for "Chinese (Traditional)_Macau S.A.R..950". I'm not sure
     * where "ZHM" comes from, must be some legacy naming scheme. But hey, it
     * works.
     *
     * Note that unlike HKG and ARE, ZHM is an alias for the *whole* locale
     * name, not just the country part.
     *
     * Some versions of Windows spell it "Macau", others "Macao".
     */
    {"Chinese (Traditional)_Macau S.A.R..950", NULL, "ZHM"},
    {"Chinese_Macau S.A.R..950", NULL, "ZHM"},
    {"Chinese (Traditional)_Macao S.A.R..950", NULL, "ZHM"},
    {"Chinese_Macao S.A.R..950", NULL, "ZHM"},
    {NULL, NULL, NULL}
};

/*
 * Mappings applied after calling setlocale(), to its return value.
 */
static const struct locale_map locale_map_result[] = {
    /*
     * "Norwegian (Bokm&aring;l)" locale name contains the a-ring character.
     * Map it to a pure-ASCII alias.
     *
     * It's not clear what encoding setlocale() uses when it returns the
     * locale name, so to play it safe, we search for "Norwegian (Bok*l)".
     */
    {"Norwegian (Bokm", "l)_Norway", "Norwegian_Norway"},
    {NULL, NULL, NULL}
};

#define MAX_LOCALE_NAME_LEN        100

static const char *
map_locale(const struct locale_map *map, const char *locale)
{
    static char aliasbuf[MAX_LOCALE_NAME_LEN];
    int            i;

    /* Check if the locale name matches any of the problematic ones. */
    for (i = 0; map[i].locale_name_start != NULL; i++)
    {
        const char *needle_start = map[i].locale_name_start;
        const char *needle_end = map[i].locale_name_end;
        const char *replacement = map[i].replacement;
        char       *match;
        char       *match_start = NULL;
        char       *match_end = NULL;

        match = strstr(locale, needle_start);
        if (match)
        {
            /*
             * Found a match for the first part. If this was a two-part
             * replacement, find the second part.
             */
            match_start = match;
            if (needle_end)
            {
                match = strstr(match_start + strlen(needle_start), needle_end);
                if (match)
                    match_end = match + strlen(needle_end);
                else
                    match_start = NULL;
            }
            else
                match_end = match_start + strlen(needle_start);
        }

        if (match_start)
        {
            /* Found a match. Replace the matched string. */
            int            matchpos = match_start - locale;
            int            replacementlen = strlen(replacement);
            char       *rest = match_end;
            int            restlen = strlen(rest);

            /* check that the result fits in the static buffer */
            if (matchpos + replacementlen + restlen + 1 > MAX_LOCALE_NAME_LEN)
                return NULL;

            memcpy(&aliasbuf[0], &locale[0], matchpos);
            memcpy(&aliasbuf[matchpos], replacement, replacementlen);
            /* includes null terminator */
            memcpy(&aliasbuf[matchpos + replacementlen], rest, restlen + 1);

            return aliasbuf;
        }
    }

    /* no match, just return the original string */
    return locale;
}

char *
pgwin32_setlocale(int category, const char *locale)
{
    const char *argument;
    char       *result;

    if (locale == NULL)
        argument = NULL;
    else
        argument = map_locale(locale_map_argument, locale);

    /* Call the real setlocale() function */
    result = setlocale(category, argument);

    /*
     * setlocale() is specified to return a "char *" that the caller is
     * forbidden to modify, so casting away the "const" is innocuous.
     */
    if (result)
        result = (char *) map_locale(locale_map_result, result);

    return result;
}
